<AWT Dev> <Swing Dev> Review request #3: 6852592 (revalidate() must be smarter)

Anthony Petrov Anthony.Petrov at Sun.COM
Mon Jul 27 10:53:56 PDT 2009

Hi Alex,

On 7/27/2009 8:41 PM Alexander Potochkin wrote:
> By the way, when isValidateRoot() method will be brought up to 
> Component, I expect the cast to be removed
> if ((c instanceof JComponent) && (((JComponent)c).isValidateRoot()))

A component cannot be a validate root by logical reasons: it has nothing 
to lay out inside itselft, and therefore the state of 
validity/invalidity is not relevant to a component. Moreover, a 
component does not have children, thus it can't be a 'root' at all. 
Therefore I expect the isValidateRoot() method to stay in the Container 
class for quite a long time.

Regarding the mentioned condition, it needs to be changed as 
s/JComponent/Container/, and so needs to be changed the code around it 
to make sure the 'c' is used as a normal AWT container w/o any special 
treatment of it as an instance of the JComponent.

> But, when addInvalidComponent() finds no vaidateRoot,
> it immediately returns, and this behavior will be affected
> I see no strong reasons to make Windows and Applets to be validate 
> roots, just because it won't give us any benefits and may break the 
> existing code

Besides, please consider a situation when one uses a few Swing 
components in an AWT application (which is rare, but not impossible). 
While this is not an 'officially supported' kind of mixing, I don't see 
reasons why it shouldn't generally work. Now suppose one of the Swing 
components is a popup (like a context menu, or a combo box, whatever). 
After displaying the popup, the Swing code is expected to call the 
revalidate() method which works perfectly in case of a Swing 
application. However, since AWT applications normally don't have 
validate roots, the addInvalidComponent() will fail to validate the 
hierarchy, and we may observe some weird stuff (we do in fact: see the 
bug 6862117). That's why I think it is OK to make the Window and the 
Applet classes validate roots. With the changes to the 
addInvalidComponent() described above, everything should work just fine.

Could you please elaborate on possible situations that could break after 
making the Window/Applet the validate root?

best regards,

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